This invention relates to an improved intrauterine contraceptive device. The object of the invention is to obtain a device which has a lower expulsion rate and is less irritative than other IUDs. There is a known IUD having the shape of a T according to U.S. Pat. No. 3,533,406. Its horizontal arms are placed into the upper part of the endometrial cavity near the fundus and the distance of the ends of horizontal arms is 30- 35 mm corresponding to the size of the portion of the uterus. The vertical arm is relatively thin having a length of 28- 36 mm. The purpose is that the device is completely placed into the endometrial cavity and the end of the vertical arm extends toward the cervical os when the crossbar of the T lies at the fundus of the uterus.
Statistics have revealed that the rate of bleeding and pain by the T device as well as by Lippes Loop is relatively high approximately 10 per cent calculated on the basis of 100 used women months. This is caused mainly by the rigidity of the mentioned devices. During the contraction of the uterus the high pressure is directed against the horizontal arms and when these arms in the T device only slightly deviate from the horizontal line a rather high pressure is needed to change its shape. This causes the relatively pointed ends of the horizontal arms to penetrate to the mucous membrane and uterus wall. This is also admitted in the above-mentioned patent which says: "X-rays studies indicate that the ends of crossbar will become slightly imbedded in the endometrium".
It is also evident that both the T and Lippes Loop are even in the vertical direction relatively rigid and cases have been found when the vertical arm of the T has penetrated into the uterus wall causing bleeding and pain.
The results of clinical tests of the T and especially by Lippes Loop show a relatively high rate of involuntary expulsions for patients wearing the device.
The object of this invention has been to decrease or eliminate the event rates mentioned above and get a higher continuation rate than other IUDs.